Medical electrical lead implant tool

ABSTRACT

A medical electrical lead implant tool includes a gripping assembly, terminating a distal end of an elongate shaft, adapted to alternately grasp the lead and release the lead and to rotate the lead, and a user control terminating a proximal end of the shaft. An internal drive cable extends within the shaft coupling the gripping assembly to the user control. The user control facilitates single-handed manipulation of a slidable dial, which may be grasped by fingers of a hand for longitudinal and rotational manipulation when a stationary handle is held in a palm of the hand; the longitudinal manipulation causing the gripping assembly, via the drive cable, to alternately grasp the lead and release the lead and the rotational manipulation causing the gripping assembly, via the drive cable, to rotate the lead.

FIELD OF THE INVENTION

The present invention relates generally to a medical electrical leadimplant tool, and more particularly to a tool facilitating theimplantation leads having at least one fixation helix or the like inareas not readily accessible during surgery.

BACKGROUND OF THE INVENTION

It is well known in the medial field that electrode leads capable ofdelivering electrical shocks may be implanted in a patient's body tostimulate a particular area or organ therein. Such leads may bepositioned, for example, proximate a patient's heart to treat very fast,and potentially lethal, cardiac arrhythmias. Typically, such epicardialleads are coupled to an implantable cardiac device (ICD) whichcontinuously monitors the heart's electrical signals and senses if, forexample, the heart is beating dangerously fast. If this condition isdetected, the ICD can deliver one or more electric shocks within a fewseconds to return the heart to a normal heart rhythm.

Electrode leads of the type described above may be secured within apatient's body by at least one fixation helix. This fixation deviceoften serves as an electrode and is inserted (i.e. screwed) into an areaof human tissue such as an epicardial surface. Implant tools capable ofguiding an electrode lead to and rotating the attached fixation helixinto an implant site are known and typically comprise a distal grippingassembly for engaging (i.e. loading) part of a lead (e.g. the head)coupled to a proximal handle. During implantation, a surgeon engages alead with the tool, positions it at the implant site, implants the lead(i.e. screws the lead's fixation helix into an area of tissue), andlastly disengages the lead from the tool. In some cases implantation maybe accomplished by rotating the entire tool, but, in many cases, whereinthe site of implantation is not readily accessible (e.g. a posteriorepicardial surface accessed via a thoracotomy), this is not practical.Thus, to facilitate the implant of electrical leads indifficult-to-reach areas, implant tools, which permit remote rotation ofthe gripping assembly, have been developed. It is desirable to provide alead implant tool that may be effectively utilized with one hand for theengagement, positioning, implant (e.g. via remote rotation of thegripping assembly), and disengagement of an electrical lead.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will hereinafter be described in conjunction withthe following figures, wherein like reference numerals denote likeelements, and

FIGS. 1, 2, and 3 are side, top, and end plan views, respectively, of anelectrode lead implant tool in accordance with the present invention;

FIG. 4 is a general side cross-sectional view of the electrode leadimplant tool shown in FIGS. 1-3;

FIG. 5 is a detailed side cross-sectional view of the shaft, nose piece,and gripping assembly of the electrode lead implant tool shown in FIGS.1-4;

FIG. 6 is a detailed side cross-sectional view of a portion of thehandle and shaft guide member of the electrode lead implant tool shownin FIGS. 1-5; and

FIG. 7 is schematic of the electrode lead implant tool shown in FIGS.1-6 positioning a lead electrode for implantation.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description of the invention is merely exemplaryin nature and is not intended to limit the scope, applicability, orconfiguration of the invention in any way. Rather, the followingdescription provides a convenient illustration for implementing anexemplary embodiment of the invention. Various changes to the describedembodiment may be made in the function and arrangement of the elementsdescribed herein without departing from the scope of the invention.

FIG. 1 is a side plan view of a medical electrical lead implant tool 200according to one embodiment of the present invention. FIG. 1 illustratestool 200 including a gripping assembly 202, formed by a nose piece 222and tongs 216 and 218, and medial shaft portion 204, extendingproximally from nose piece 222, each of which are similar to thosedescribed in commonly assigned U.S. Pat. No. 6,010,526 which isincorporated by reference in its entirety herein. FIG. 1 furtherillustrates tool 200 including a user control terminating a proximal endof medial shaft portion 204; the user control is configured forsingle-handed operation and includes a slidable dial 212, a shaft guidemember 206, and a stationary handle 210. The proximal end of shaft 204is received by an opening at a distal end of shaft guide member 206; aproximal end 232 of shaft guide member 206 expands to form a bell-shapedmouth that receives a distal end of handle 210. Specifically, proximalend 232 abuts two fingers (i.e. extensions) 258 which are distinct froma body 260 of handle 210 and extend distally from handle body 260. Theouter edges of the upper and lower interfaces formed by fingers 258 andproximal end 232 are thus substantially smooth as can be seen in FIGS. 2and 3, which are top and end plan views of implant tool 200.

Referring still to FIG. 1, it can be seen that slidable dial 212 ispositioned between fingers 258 and around a retainer rod 208, whosedistal and proximal ends are held within the proximal end of shaft guidemember 206 and the distal end of handle 210, respectively. Retainer rod208 is fixedly coupled to slidable dial 212 and may rotate and/or movelongitudinally between shaft guide member 206 and handle 210 as is morefully described hereinbelow. Access to slidable dial 212 is facilitatedvia windows 230 which are provided on either side of fingers 258 so thatimplant tool 200 is configured to enable an operator to simultaneouslygrasp proximal handle portion 210 with one hand (e.g. with the palm) andmove (i.e. rotate and/or move longitudinally) slidable dial 212 with thesame hand (e.g. with the thumb). Slidable dial 212 is shown in FIG. 3 ashaving a first, distal section of a larger diameter, which tapers inwardto a second, proximal section of a smaller diameter. Slidable dial 212is thus contoured and provided with a plurality of grooves therein tofacilitate user control (i.e. to provide a better, more ergonomic grip,etc.). It should be understood, however, that slidable dial 212 may takeany shape suitable for permitting longitudinal and rotationalmanipulation thereof.

Two fastening devices that cannot be seen in FIG. 1 may be seen in FIGS.2 and 3. FIG. 2 illustrates a fastening device 236 (e.g. a set screw)positioned within the distal portion of shaft guide member 206 to securemedial shaft 204 within shaft guide member 206. FIG. 3 illustratesanother fastening device 238 (e.g. a screw) positioned in an upper frontof the proximal end of shaft guide member 206 to couple shaft guidemember 206 to fingers 258 of handle 210. A third fastening device 240(e.g. a screw), which is positioned within lower front of the proximalend of shaft guide member 206, also couples shaft guide member 206 tohandle 210 and may be seen in FIG. 4. Although fastening devices 236,238, and 240 are shown as having particular locations along shaft guidemember 206, it should be appreciated that they may assume any suitableposition within implant tool 200 and may be accompanied by additionalfastening devices.

FIG. 4 is a side cross-sectional view of the electrode lead implant tool200 shown in FIGS. 1-3. FIG. 4 illustrates the distal end and theproximal end of shaft 204 extending substantially into nose piece 222and shaft guide member 206, respectively, and an internal drive cable242 passing through shaft 204, nose piece 222, and shaft guide member206 in order to couple gripping assembly 202 to slidable dial 212. Cable242 permits the transfer of forces (e.g. torque) from slidable dial 212to gripping assembly 202.

FIG. 5 is a detailed side cross-sectional view of gripping assembly 202and shaft 204 of the electrode lead implant tool 200 shown in FIGS. 1-4.FIG. 5 illustrates a distal end of cable 242 terminating within nosepiece 222 where cable 242 is coupled (e.g. crimped) to proximal ends oftongs 216 and 218 by means of a crimp sleeve 280. FIG. 5 furtherillustrates a toroidal bearing 256 positioned within the distal end ofnose piece 222 and extending around tongs 216 and 218; tongs 216 and 218slide along toroidal bearing 256 and are forced closer together duringcable retraction and permitted to move apart during cable extension inresponse to slidable dial 212 moving away from and closer to shaft guidemember 206, respectively. It should thus be understood that longitudinalmovement of slidable dial 212 in a first direction (i.e. away from shaftguide member 206) causes the distal ends of tongs 216 and 218 to movetoward nose piece 222 and therefore closer to one another. Longitudinalmovement of slidable dial 212 in the opposite direction (i.e. towardshaft guide member 206) causes the distal ends of tongs 216 and 218 toextend from nose piece 222 and move away from each other. In thismanner, slidable dial 212 may be manipulated to cause tongs 216 and 218to engage (i.e. grip) and disengage (i.e. release) a lead.

FIG. 6 is a detailed side cross-sectional view of handle 210 and shaftguide member 206 of the electrode lead implant tool 200 shown in FIGS.1-5. FIG. 6 illustrates a proximal end of cable 242 extending into shaftguide member 206 and received therein by a sleeve 246; cable 242 issecured therein by a compression means 270 (e.g. a set screw) thatcompresses sleeve 246 so that an inner surface thereof frictionallyengages an outer surface of cable 242. It can be seen in FIG. 6 thatsleeve 246 is secured within retainer rod 208, which is, in turn,fixedly coupled to slidable dial 212. Thus, force applied to slidabledial 212 is transferred through retainer rod 208, sleeve 246, and cable242 to tongs 216 and 218.

FIG. 6 further illustrates handle 210 including an annular extension250, which extends distally near the distal end of handle body 260,around the proximal end of retainer rod 208 and is partly received by acavity provided within a proximal end of slidable dial 212. Slidabledial 212 may rotate and/or move longitudinally relative to annularextension 250; however, slidable dial 212 is prevented from extending sofar as to disengage from annular extension 250 (e.g. by the proximal endof shaft guide member 206). Annular extension 250 thus helps maintainthe positioning of retainer rod 208 and slidable dial 212 withoutinterfering with the rotational and/or longitudinal movement thereof.

As can be further seen in FIG. 6, an internal cable tension spring 262is provided within shaft guide member 206, a proximal end of which abutsretainer rod 208 while a distal end thereof abuts an inner step or wallof shaft guide member 206. According to the illustrated embodiment,retainer rod 208 moves along with slidable dial 212 such that a distalmovement of slidable dial 212 (i.e. towards shaft guide member 206)results in the compression of cable tension spring 262; once a forcesufficient to move slidable dial 212 towards shaft guide member 206 isremoved, spring 262 will expand proximally to force slidable dial 212away from shaft guide member 206. As has been described hereinabove,movement of slidable dial 212 away from shaft guide member 206 resultsin the corresponding movement of tongs 216 and 218 in the direction ofnose piece 222 and toward each other. A user of implant tool 200 maythus push slidable dial 212 towards shaft guide member 206 to open tongs216 and 218, and then release slidable dial 212 (i.e. cease applying alongitudinal force thereto) to allow tongs 216 and 218 to close around alead. If a lead is engaged as tongs 216 and 218 close, the implant willbe secured therebetween by the tension generated by spring 262. In thisway, tongs 216 and 218 may maintain a grip on an implant until anoperator chooses to release the implant by once again sliding slidabledial 212 towards shaft guide member 206.

It should thus be understood that tool 200 may utilized to engage orgrip, position, implant, and disengage from or release a lead having afixation helix affixed thereto in the manner suggested in FIG. 7. FIG. 7illustrates a medical electrical lead 370 including a fixation helix 374extending from a head 376 which is coupled to a lead body 378; head 376is engaged by tongs 216 and 218 of implant tool 200 and positioned viashaft 204 of tool 200 for implantation in an epicardial surface 372.Insulative lead body 378 contains an elongated conductor that is coupledto fixation helix 374, which serves as an electrode. Fixation helix 374extends downward from a lower surface of lead head 376, which carriesaround its external periphery a mesh skirt 380 (e.g. made of a DACRONfiber).

According to embodiments of the present invention, engagement of leadhead 376 is accomplished by first pushing slidable dial 212 toward shaftguide member 206, resulting in the compression of cable tension spring262 and the opening of tongs 216 and 218. The distal ends of tongs 216and 218 are then placed proximate lead head 376 and allowed to close(i.e. the longitudinal force applied to slidable dial 212 is removed).Engagement is maintained as cable tension spring 262 attempts to expandthereby placing a constant gripping tension on the distal ends of tongs216 and 218. After lead engagement, shaft 204 is maneuvered to positiontongs 216 and 218 in proximity to epicardial surface 372 so as toposition fixation helix 374 at an implant site. After helix 374 isimplanted in epicardial surface 372, via rotation of slidable dial 212,lead head 376 is released by once again by longitudinally movingslidable dial 212 toward shaft guide member 206 and causing the distalends of tongs 216 and 218 to separate.

Finally, it will be appreciated by those skilled in the art that whilethe invention has been described above in connection with a particularembodiment, the invention is not necessarily so limited; numerous otherembodiments and uses are intended to be encompassed by the claimsattached hereto.

1. A medical electrical lead implant tool, comprising: an elongate shaftincluding a proximal end and a distal end; a gripping assemblyterminating the distal end of the shaft and adapted to alternately graspthe lead and release the lead and to rotate the lead; a drive cablecoupled to the gripping assembly and extending proximally therefromwithin the shaft; and a user control terminating the proximal end of theshaft and including a shaft guide member coupled to the shaft, astationary handle coupled to the shaft guide member, a slidable dialcoupled to a proximal end of the drive cable and positioned in betweenthe shaft guide member and the stationary handle, and an aperture formedbetween the shaft guide member and the handle to expose the slidabledial; wherein the user control facilitates single-handed manipulation ofthe slidable dial, which may be grasped by fingers of a hand forlongitudinal and rotational manipulation when the stationary handle isheld in a palm of the hand; the longitudinal manipulation causing thegripping assembly, via the drive cable, to alternately grasp the leadand release the lead and the rotational manipulation causing thegripping assembly, via the drive cable, to rotate the lead.
 2. The toolaccording of claim 1, wherein said shaft is curved.
 3. The tool of claim1, wherein the gripping assembly comprises a pair of tongs and whereinthe longitudinal manipulation of the slidable dial in a first directioncauses the tongs to spread apart to release the lead.
 4. The tool ofclaim 3, wherein said first direction is a distal direction.
 5. The toolof claim 3, wherein the first direction is a proximal direction.
 6. Thetool of claim 3, wherein the user control further includes a resilientelement mounted therein for normally biasing the slidable dial to alongitudinal position wherein the tongs are forced together to grasp thelead.
 7. The tool of claim 1, wherein the user control further includesa retainer rod extending within the shaft guide member and coupling theslidable dial to the proximal end of the drive cable.
 8. The tool ofclaim 1, wherein the stationary handle includes an inner annularextension received in a cavity formed at a proximal end of the slidabledial.